US4780773A - Motor control circuit with current limiter and bypass switch - Google Patents

Motor control circuit with current limiter and bypass switch Download PDF

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Publication number
US4780773A
US4780773A US07/037,147 US3714787A US4780773A US 4780773 A US4780773 A US 4780773A US 3714787 A US3714787 A US 3714787A US 4780773 A US4780773 A US 4780773A
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United States
Prior art keywords
motor
turning speed
output signal
current
driving circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/037,147
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English (en)
Inventor
Keizo Hama
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Filing date
Publication date
Priority claimed from JP61086350A external-priority patent/JPH0697537B2/ja
Priority claimed from JP11550886A external-priority patent/JPS62271253A/ja
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Assigned to MITSUBISHI DENKI KABUSHIKI KASHA reassignment MITSUBISHI DENKI KABUSHIKI KASHA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HAMA, KEIZO
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/20—Driving; Starting; Stopping; Control thereof

Definitions

  • the present invention relates to a spindle motor driving apparatus for a disc device, and more particularly, to improvements in the starting rising characteristics of a spindle motor.
  • FIG. 1 shows a block diagram of a prior-art driver for driving a motor of a disc device.
  • numeral 1 designates a spindle motor (hereinbelow, termed “motor”), which drives one or a plurality of magnetic discs, not shown
  • numeral 2 designates a spindle motor driving circuit (hereinbelow termed, "a driving circuit”), which drives the motor 1 and includes a pair of upper and lower transistors Q 1 and Q 2 to drive one phase of the motor 1 and a a motor current detecting resistor R which is used to control current for turning the motor.
  • Numeral 3 designates a rotary angle position sensor necessary to decide the direction of driving current to the motor 1 and to detect a driving current flowing zone and motor turning speed.
  • the rotary angle position sensor may for example, employ a Hall element.
  • the output of the sensor 3 is input to a turning speed comparator 4, which compares the output of the sensor 3 with the output of a target turning speed generator 5 to control the turning speed of the motor 1 constantly.
  • Numeral 6 designates a current limiter for protecting the transistors of the driving circuit 2
  • numeral 7 designates a d.c. power supply, which supplies current to drive the motor 1.
  • the above-described prior-art is a general constant motor turning speed control circuit, and the function of the current limiter 6 will be further described.
  • the d.c. resistance of one-phase shunt winding of the motor 1 having, for example, approx. 1/8 horsepower is approx. 0.6 ohm. Therefore, if the current limiter 6 is not provided, the current flowing to the motor 1 at the starting time becomes a value which is calculated by dividing the output voltage of the power supply 7 by the d.c. resistance and the current detecting resistor R (valued at approximately 0.1 ohm), and becomes, for example, as below. ##EQU1##
  • the current flowing to the motor 1 is, on the other hand, approx. 3.4 A when the motor 1 is rotated under control of the steady-state turning speed such as, for example, 3,600 r.p.m., and the inflowing current ratio of the current at the starting time to the current at the steady-state time is large.
  • the driving circuit 2 is largely loaded, and the cost of the transistors Q 1 and Q 2 of the final stage of the driving circuit 2 is thus raised.
  • the current limiter 6 has been used.
  • the driving circuit 2 is improved by the operation of the current limiter 6, but since the limiter 6 is inserted in series between the d.c. power supply 7 and the load, i.e., between the driving circuit 2 and the motor 1, a disadvantage is that the electric power is always lost to disturb the high efficiency of driving the motor with the same power supply capacity.
  • FIG. 1 is a circuit diagram of a prior-art
  • FIG. 2 is a circuit diagram showing an embodiment of a spindle motor driver for a magnetic disc device according to the present invention
  • FIG. 3 is a diagram showing motor characteristics
  • FIG. 4 is a block diagram of the spindle motor driver of the invention.
  • FIG. 5 is a flow chart showing the concept of the embodiment of FIG. 2;
  • FIG. 6 is a circuit diagram showing another embodiment of a spindle motor driver for a magnetic disc device according to the invention.
  • FIG. 7 is a flow chart showing the concept of the embodiment of FIG. 6.
  • the present invention has the objective of overcoming the disadvantage of the prior art as mentioned above, and has for its main object to provide a spindle motor driving apparatus for a magnetic disc device in which the load imposed on a power supply by the motor driving apparatus is reduced, the efficiency of a driving apparatus is enhanced and the starting characteristics of the motor is further improved.
  • the spindle motor driving apparatus for the magnetic disc device includes a switching instruction unit setting the condition for closing a shorting switch provided in a current limiter inserted in series between a power supply and the driving apparatus in response to the operating state of the motor.
  • numeral 8 designates a switching indicator, which outputs a signal corresponding to an optimum preset driving time for shorting a current limiter 6 by a switch 9 and applying an output voltage of the power supply 7 to a deciding unit 10 and to all loads, i.e., the driving circuit 2 and motor 1.
  • the deciding unit 10 compares in amplitude the signal output of the indicator 8 with the signal output of a starting time measuring unit 11 for measuring the start elapsing time of the motor 1 and produces a signal output to the switch 9 to close the switch 9 when the start elapsing time becomes long or it becomes a preset driving time.
  • FIG. 3 shows the operation of this embodiment in FIG. 2.
  • the ordinate axis indicates the turning speed N of the motor 1 and current (consumed current) I flowing to the motor 1.
  • the abscissa axis indicates a start elapsing time t.
  • broken line curves indicate an example of the operation of a prior-art driver
  • solid line curves indicate an example of operation of the embodiment of the invention.
  • the current I remains a value I 1 since the motor is limited to cause the current to flow in a range from time t 0 to t 1 after the motor starts, and it is thus understood that the operation of the current limiter 6 is effective.
  • the current is affected by the influence of a counterelectromotive force generated by the rotation of the motor 1 in a range after the time t 1 , i.e., the current continues to decrease in the amount corresponding to the reduction in the effective voltage applied to the motor 1, and this state continues until the current becomes a steady-state current value I 2 to the time t 2 and hence the motor arrives at the specified turning speed N 1 .
  • the reduction in the counterelectromotive force of the motor 1 can be even slightly supplemented, i.e., if the effective voltage to the motor 1 can be raised, the starting characteristic of the motor 1 can be improved.
  • the voltage drop of the current limiter 6 is used as the effective voltage rise to the motor 1.
  • the operation of the embodiment is exemplified with reference to the solid line curves in FIG. 3.
  • the start arriving time to 3,600 r.p.m.of target turning speed of the motor is improved from 55 sec. (t 2 ) to 25 sec. (t 4 ).
  • the motor driving circuit is constructed to utilize the voltage drop of the current limiters inserted in series between the d.c. power supply and the load as the effective voltage of the motor in a range after the motor of the load arrives at the specified driving time. Therefore, the motor driving circuit is inexpensive to save the electric power and to improve the motor starting characteristics.
  • FIG. 4 shows an example applied to an actual product of the embodiment of the invention.
  • Numeral 20 designates an 8 bit microcomputer ( ⁇ CPU), which uses, for example, an M5L8039P chip made by Mitsubishi Electric Corp.
  • Numeral 21 designates a Read Only Memory (ROM), which uses, for example, an M5L2764K chip made by Mitsubishi Electric Corp.
  • Numeral 22 designates a Programmable Interval Timer (PIT) which uses, for example, an M5L8253P chip made by Mitsubishi Electric Corp.
  • Numeral 23 designates an Octal Latch (OL) which is ordinarily used in a microcomputer system. This example operates as below.
  • the sensor 3 When the spindle motor 1 in FIG. 2 starts rotating, the sensor 3 generates one pulse by one revolution of the motor and starts feeding a signal on the ⁇ CPU 20 in FIG. 4.
  • the ⁇ CPU 20 detects the start of the rotation of the motor 1 by the output of the sensor 3 and then decides the closing time of the switch 9 in the following sequence.
  • the uCPU 20 reads the predetermined value corresponding to the closing time t 3 of the switch 9 from the ROM 21 and instructs to start measuring the driving lapse time of the motor 1 of the PIT 22.
  • An octal latch 23 has the function of an address latch for latching data on a data bus.
  • FIG. 5 is a flow chart showing the above-described operation, showing that the closing instruction of the switch is made when the condition that a predetermined time is elapsed is satisfied after the motor is started.
  • FIG. 6 is a block diagram showing the construction of another embodiment of the invention, wherein the same symbols as those in FIG. 1 showing a prior-art driver indicate the same or corresponding parts.
  • Numeral 12 designates a switching turning speed indicator
  • numeral 9 designates a switch
  • numeral 13 designates a deciding unit.
  • the indicator 12 is set to output a signal when the turning speed of the spindle motor 1 arrives at a predetermined value
  • the deciding unit 13 compares the signal output of a rotary angle position sensor 3 with the signal output of a switching turning speed indicator 12, and decides that the turning speed of the motor 1 exceeds the turning speed set to the indicator 12 to output a signal.
  • the switch 9 is connected in parallel with a current limiter 6, and closed in response to the output signal of the deciding unit 13.
  • the operation of this embodiment will be described together with reference to FIG. 3.
  • the current I flowing to the motor 1 is limited to I 1 by the current limiter 6 in a range from the time t 0 to t 1 immediately after the motor 1 is started, and the limiter 6 effectively operates.
  • the turning speed N of the motor 1 gradually rises after the time t 1 so that the counterelectromotive force of the motor increases, the current I flowing to the motor gradually decreases.
  • the deciding unit 13 When the turning speed N of the motor 1 then arrives at the turning speed Nc set to the indicator 12, the deciding unit 13 generates a signal. Thus, the switch 9 is closed to short the current limiter 6. Since the full voltage of the d.c. power supply 7 is applied to the spindle motor driving circuit 2 at this moment, the current I flowing to the motor abruptly increases from the time t 3 , but as the current I rises, the turning speed N of the motor also increases. Therefore, the current I flowing to the motor decreases soon. The turning speed N of the motor becomes the specified turning speed N 1 at the time t 4 , and the current I flowing to the motor becomes a rated current I 2 .
  • the current continuously flows to the current limiter 6, and only the voltage calculated by subtracting the voltage drop of the current limiter from the d.c. power supply voltage is applied to the motor driving circuit 2.
  • the turning speed N of the motor 1 becomes the spedified turning speed N 1 at the time t 2 and the current I flowing to the motor becomes a rated current I 2 as designated by broken line curves in FIG. 3.
  • a d.c. power supply 7 of 36 V is prepared for the spindle motor of 1/8 horsepower and the resistance of the current limiter 6 is 2 ohms. If the switching turning speed indicator 12 is set to 2,000 r.p.m. when the rated turning speed of the motor 1 is 3,600 r.p.m., the starting time of the prior-art driver is 55 sec. of t 2 , while that of this embodiment can be shortened to 25 sec. of t 4 .
  • FIG. 7 is a flow chart of this case. When the turning speed of the motor arrives at a predetermined value, the switch is instructed to be closed.

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US07/037,147 1986-04-15 1987-04-10 Motor control circuit with current limiter and bypass switch Expired - Fee Related US4780773A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP61-86350 1986-04-15
JP61086350A JPH0697537B2 (ja) 1986-04-15 1986-04-15 磁気デイスク装置
JP61-115508 1986-05-20
JP11550886A JPS62271253A (ja) 1986-05-20 1986-05-20 磁気デイスク装置

Publications (1)

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US4780773A true US4780773A (en) 1988-10-25

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Family Applications (1)

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US07/037,147 Expired - Fee Related US4780773A (en) 1986-04-15 1987-04-10 Motor control circuit with current limiter and bypass switch

Country Status (3)

Country Link
US (1) US4780773A (fr)
DE (1) DE3712769A1 (fr)
FR (1) FR2597250B1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4879498A (en) * 1986-08-06 1989-11-07 Fujitsu Limited DC motor drive system for reducing start-up current
US4952854A (en) * 1988-01-19 1990-08-28 Rockwell-Cim Control device for a DC motor intended for in particular driving opening elements on automobile vehicles
EP0400675A2 (fr) * 1989-06-01 1990-12-05 Sony Corporation Circuit excitateur pour un organe de commande
US5218491A (en) * 1990-06-26 1993-06-08 Sony Corporation Disk drive apparatus
US5298840A (en) * 1991-07-15 1994-03-29 Rohm Co., Ltd. Motor control circuit and motor drive system using the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SG47680A1 (fr) * 1990-02-06 1998-04-17 Seagate Technology

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4611252A (en) * 1982-06-16 1986-09-09 Matsushita Electric Industrial Co., Ltd. Video tape recorder
US4706005A (en) * 1985-04-09 1987-11-10 Citizen Watch Co., Ltd. Control circuit of direct current servomotor for floppy disk drive

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT89021B (de) * 1916-01-29 1922-07-25 Siemens Schuckertwerke Wien Anlaßeinrichtung für Gleichstrom-Nebenschlußmotoren.
JPS5322704A (en) * 1976-08-16 1978-03-02 Hitachi Ltd Rotation damping device of tu rntable
FR2466075A1 (fr) * 1979-09-21 1981-03-27 Philips Ind Commerciale Tourne-disque a plateau directement entraine par son moteur
GB2077961A (en) * 1980-06-13 1981-12-23 Bsr Ltd Turntable speed control
JPS57183281A (en) * 1981-05-06 1982-11-11 Nec Corp Controlling circuit for number of revolution
JPS60113680A (ja) * 1983-11-22 1985-06-20 Victor Co Of Japan Ltd モ−タの回転制御装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4611252A (en) * 1982-06-16 1986-09-09 Matsushita Electric Industrial Co., Ltd. Video tape recorder
US4706005A (en) * 1985-04-09 1987-11-10 Citizen Watch Co., Ltd. Control circuit of direct current servomotor for floppy disk drive

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4879498A (en) * 1986-08-06 1989-11-07 Fujitsu Limited DC motor drive system for reducing start-up current
US4952854A (en) * 1988-01-19 1990-08-28 Rockwell-Cim Control device for a DC motor intended for in particular driving opening elements on automobile vehicles
EP0400675A2 (fr) * 1989-06-01 1990-12-05 Sony Corporation Circuit excitateur pour un organe de commande
EP0400675A3 (fr) * 1989-06-01 1991-07-17 Sony Corporation Circuit excitateur pour un organe de commande
US5218491A (en) * 1990-06-26 1993-06-08 Sony Corporation Disk drive apparatus
US5298840A (en) * 1991-07-15 1994-03-29 Rohm Co., Ltd. Motor control circuit and motor drive system using the same

Also Published As

Publication number Publication date
FR2597250A1 (fr) 1987-10-16
DE3712769A1 (de) 1987-10-22
DE3712769C2 (fr) 1989-09-07
FR2597250B1 (fr) 1991-04-26

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